Some infrastructure platforms use mixed-case keys for environment variables, and do case-sensitive checks. In order to support syncing secrets to these platforms, Doppler needs to support mixed-case keys.
While I understand wanting to only support UPPER_CASE keys to maintain cross-shell support, this makes Doppler unusable for some deployments. A warning when trying to inject an invalid secret for a shell that doesn’t support that casing could provide sufficient balance against the functionality gained.
In my case, I’m wanting to deploy an Azure Function App using secrets from Doppler. This requires a critical app setting under the name “AzureWebJobsStorage”. Without this setting existing under that exact casing, the whole deployment fails, and will kill any existing deployment.
See this Github issue: https://github.com/Azure/functions-action/issues/93.
As seen in this article, there are 11 settings that need mixed case keys.